Insulated nestable container and method of making the same



Aug. 31, 1965 T. F. ANDERSON ETAL 3,203,611

INSULATED NESTABLE CONTAINER AND METHOD OF MAKING THE SAME Filed July10, 1962 3 Sheets-Sheet l INVENTORS THOMAS F. Auouzgou I DMQD C. TQlMbLE DONALD 21.5mm; Eowm B. HOFFMAN ATTORNEYS Aug. 31, 1965 T. F.ANDERSON ETAL 3,203,611

INSULATED NESTABLE CONTAINER AND METHOD OF MAKING THE SAME Filed July10, 1962 3 Sheets-Sheet 2 Fig. 8

72 5a so INVENTORS THOMAS F Ammww 5 m m 5m m NF 0 E m .B C DM D AME DDONALDHSTOQEY BY 5 Aug. 31, 1965 T. F. ANDERSON ETAL INSULATED NESTABLECONTAINER AND METHOD OF MAKING THE SAME 3 Sheets-Sheet 3 Filed July 10,1962 INVENTORS I00 THoMA5 FT ANQEQWN DAVID C- TQIMEBLE, m B. HOFFMANATTORNEYS DONALD HSTOREY i Euw BY ted States Patent 3,245,611 INSULATEDNESTABLE KCGNTAINER AND METHOD OF MAKING THE SAW Thomas F. Andersen,Wilmington, David (I. Trimble,

Yorklyn, and Donald H. Storey and Edwin B. Hotfman,

Wilmington, DeL, assignors to Haveg Industries, lino,

a wholly-owned subsidiary of Hercules Powder Company, New Castle, Del, acorporation of Delaware Filed July 10, 1962, Ser. No. 208,866 4 Claims.(Cl. 229-) This invention relates to plastic containers and moreparticularly to thin-walled plastic containers such as drinking cups andthe like and an improved method for making the same.

There are currently available a great variety of plastic containers fora great variety of ditferent uses. A large portion of these containersare made by a simple injection molding procedure wherein the plasticmaterial is simply fed between cooperating male and female molds andafter either curing or hardening the molded container is removed fromthe molds. Contamers made in this Way can be used to good advantagewhere reusage is contemplated and high cost is not a significant factor.In those applications where the containers are to be used only once andthen thrown away cost is an important factor, as for example, containersutilized in vending machines and in the carry out restaurant business.It has been found advantageous mainly from a cost point of view, to formsuch containers from a plastic sheet or film by drawing the sheet orfilm into suitable molds. This latter procedure is more economical,primarily for the reason that it is possible to form .a containerutilizing a minimum amount of plastic material. Assuming that massproduction techniques can be utilized, a major fac tor in determiningthe economy of production is the amount of plastic material which isrequired to form the container. Where injection molding procedures areutilized, the wall thickness of the container cannot be held to the sameminimum requirements as is the case where a drawing procedure isemployed. That is, it has not been found to be commercially feasible toform the Wall of a container by injecting a plastic material betweencooperating male and female dies without providing a relative.y thickminimum wall thickness. When utilizing a drawing procedure the Wallthickness can be considerably less than when an injection moldingprocedure is employed, due to the fact that .it is not necessary to formthe wall between the cooperating die surfaces.

For the reasons indicated above, drawn plastic containers have receivedwidespread acceptance in vending machine operation as well as carry outtype operations. T he containers used in vending machines presentprobably the most severe requirements, particularly where the machinesare dispensing hot beverages. In this application, a thin walledcontainer is not only desirable from the standpoint of cost, but fromthe standpoint of being able to store a maximum number of containersWithin a given space.

It will be appreciated that an important consideration in determiningstacking tolerances is the thickness of the walls of the container.Another factor in this regard is the angle of taper of thefrusto-conical side wall of the container. This angle of taper in aliquid container is limited to the inherent physical requirements of thecontainer. That is, the taper cannot be too great or else the bottomsurface will be too small to stably support the container with liquidtherein. Thus, within the requirements necessary for the taper of thewall, the stacking height can be minimized by providing a minimum wallthickness. However, where very hot drinks are involved, a very thin wallprovides the disadvantage of too ice great a heat transfer, thusrendering the container uncomfortable to handle.

There have been several attempts to alleviate this problem. For example,the container Walls have been provided with various configurations whichprovide a minimum heat transfer to the user. An example of a cup of thistype is disclosed in James R. Caine application Serial No. 711,739,filed January 28, 1958, now Patent No. 3,045,887.

Of course, the heat transfer problem can be overcome by suflicientlyincreasing the Wall thickness but this does not constitute the completesolution, because of the fact that increased wall thickness results inan increased stacking height and therefore a considerably lesser numberof cups can be stored in the vending machine. For example, there arecurrently available on the market several containers which are formedentirely of a foamed plastic such as foamed polystyrene. In general,these containers are formed in cooperating male and female dies byprocedures similar to compression molding and have a substantialthickness throughout. Indeed, the increased stacking height provided bysuch cups is such that they have not been adopted for vending machineuse. Moreover, the softness of the foam material presents ditlic-ultiesin mechanical handling.

Qther proposals have been made to provide a container which would besatisfactory under the demanding conditions indicated above, forexample, various containers formed primarily of paper are currentlyavailable. While these containers may provide slightly better heattransfer properties than thin walled plastic containers and are of suchwall thickness as to present a favorable stacking height, neverthelessthey present the disadvantage that many consumers object to the papertaste, particularly when drinking hot coffee or other hot drinks. Therehave been many efforts to overcome this disadvantage, but to date theyhave not been entirely satisfactory. For example, it has been proposedto provide a plastic coating over such paper containers and to laminatecertain plastics on the paper. This type of approach has not beenentirely acceptable, and of course, adds to the costs involved.

An object of the present invention is the provision of a thin-walledplastic container which will meet the demanding requirements for hotbeverage vending machines by providing a Wall sturcture having a minimumthickness so as to thereby minimize the stacking height, which wallconstruction will provide adequate heat transfer properties to enablethe user to handle the container filled with a hot beverage with verylittle or no discomfort.

Another object of the present invention is the provision of a containerof the type described provided with a gripping portion including afoamed plastic capable of expanding to increase the insulationporperties of the container in response to increases in the temperatureof the material contained therein.

Another object of the present invention is the provision of a containerof the type described having improved structure embodied therein forenabling a series of such containers to be nested in stacked relation ina minimum height so that they may be freely removed from such stackwithout adjacent containers sticking together.

Another object of the present invention is the provision of a novelmethod of producing the containers of the type described which includesthe steps of depositing a pre formed blank of foamed plastic in a dieand drawing a plastic sheet or film into the die so as to adhere to thepre-formed blank and conform to the configuration of the die.

Still another object of the present invention is the provision of anovel procedure for forming a pro-formed blank of foamed plastic in atubular shape.

These and other objects of the present invention will become moreapparent during the course of the foilowing detailed description andappended claims.

The invention may best be understood with reference to the accompanyingdrawings wherein an illustrative embodiment is shown.

In the drawings:

FIGURE 1 is a perspective view of a container em bodying the principlesof the present invention;

FIGURE 2 is an enlargerd top plan View of the container;

FIGURE 3 is a vertical sectional View showing two containers in stackedrelation;

FIGURE 4 is an enlarged fragmentary cross-sectional view taken along theline 4-4 of FIGURE 3;

FIGURE 5 is a view similar to FIGURE 4 illustrating a modified form ofthe container;

FIGURE 6 is an elevational view of a modified form of containerembodying the principles of the present invention;

FIGURE 7 is an enlarged fragmentary cross-sectional View taken along theline 7-7 of FIGURE 6;

FIGURE 8 is a top plan view of the foamed plastic sheet materialillustrating the manner in which the blank pieces are severed therefrom;

FIGURE 9 is an enlarged fragmentary cross-sectional view taken along theline 9-9 of FIGURE 8;

FIGURE 10 is a perspective view illustrating the foamed plastic blank inits opened condition preparatory to insertion within the die cavity;

FIGURE 11 is a view similar to FIGURE 10 illustrating a modified form ofthe blank;

FIGURE 12 is an enlarged fragmentary view illustrating anotherembodiment of a foamed sheet material which may be utilized in makingthe container of the present invention;

FIGURE 13 is a view similar to FIGURE 12 showing still another modifiedform of the sheet material;

FIGURE 14 is a vertical sectional view of the die cavity of a moldutilized in carrying out the method of the present invention, showingthe blank inserted therein;

FIGURE 15 is a view similar to FIGURE 14 illustrating the manner inwhich the plastic sheet is mounted over the die cavity;

FIGURE 16 is a view similar to FIGURE 15 illustrating the manner inwhich the plastic sheet is mechanically moved into the die cavity;

FIGURE 17 is a View similar to FIGURE 16 illustrating the manner inwhich the plastic sheet is drawn into conformity with the blank and thewalls of the die cavity; and

FIGURE 18 is a fragmentary view similar to FIGURE 17 illustrating themanner in which the formed container is severed from the sheet while inthe die cavity.

Referring now more particularly to the drawings, there is shown inFIGURES 1-4 a container, generally indicated at 10, which embodies theprinciples of the present invention. The container 10 is made up of abody which includes a bottom 12 and an upwardly and outwardly taperingfrusto-conical peripheral wall 14 extending upwardly from the peripheraledge of the bottom and terminating in a radially outwardly extendingperipheral rim 16 defining an open top. The peripheral wall 14 ispreferably made up of a laminated construction including an inner wallportion 18 which is preferably formed integral with and of the samematerial as the bottom 12. Secured to the exterior surface of the innerwall portion 18 is an outer wall portion 29 which is of foamed plasticconstruction. As shown, the outer wall portion 20 has a multiplicity ofopenings extending therethrough, as indicated at 22.

As best shown in FIGURES 1-3, formed at the bottom 12. is a stackingmeans, generally indicated at 24, providing vertically spaced upwardlyand downwardly facing stacking surface means, the upwardly facingsurfaces serving to engageably receive the downwardly facing surfaces ofa similar container so as to support the similar container in nestedrelation therein, as shown in FIGURE 3, wherein the peripheral wall 14of the nested container is freely fitted within the peripheral wall ofthe container receiving the same so as to permit substantially freeseparation of the nested containers. As shown, the bottom 12 is formedto provide the stacking means 24 with a horizontal relatively narrowperipheral rim portion 2a which provides the means for supporting thecontainer on a horizontal supporting surface. Preferably, the rimportion 26 is provided with a radially extending groove 28 therein whichprovides a vent for the passage of air into and out of the space beneaththe bottom when it is resting on a horizontal surface.

While the stacking means 24 described above and shown in the drawingsconstitutes a preferred embodiment, it will be understood that otherstacking means may be employed. For example, a stacking means of thetype shown and described in the above-mentioned Caine application couldbe embodied in the peripheral wall 14 of the container 16 adjacent thebottom 12 in lieu of the stacking means. In this case, the lower edge ofthe blank would extend to the upper edge of the stacking means.

Extending inwardly and upwardly at a relatively shallow angle from theinner periphery of the rim portion 26 is an annular wall section 36. Theupwardly facing surfaces of the stacking means 24 are provided by a pairof horizontally extending spaced, wall sections 32 of segmental arcuateconfiguration. The arcuate edges of the wall sections 32 areinterconnected with the inner edges of the annular wall section 30 byupwardly and inwardly tapering arcuate wall sections 34. The straightedge of each wall section 32 has a wall section 36 which extendsdownwardly and outwardly therefrom, the end of each wall section 36being interconnected with the adjacent end of the arcuate wall section34 by a triangular shaped vertical wall section 38. Finally, the loweredges of the wall sections 36 and 38 are interconnected by a shallowinverted V-shaped wall section 46, the latter providing the downwardlyfacing stacking surfaces of the stacking means 24.

Referring now more particularly to FIGURE 4, it can be seen that theperipheral rim 16 includes an inner annular rim portion 42 extendinggenerally radially outwardly from the peripheral wall and an outerannular rim portion 44 extending upwardly from the outer edge of theinner rim portion. A modified construction of the annular rim 16 isshown in FIGURE 5 and indicated at 16' wherein there is provided aturned under rim portion 46 so as to provide a rounded mouth-engagingedge to the container.

Referring now more particularly to FIGURES 6 and 7, there is showntherein a modified form of the container, generally indicated at It),embodying the principles of the present invention. The container ill isidentical to the container 10 previously described except that theperipheral wall, indicated at 14, includes a foamed plastic outerperipheral wall portion 20' which is pro vided with a series of spacedlongitudinally extending grooves embossed therein, as indicated at 48.

The present invention also includes a preferred method of forming thecontainers described above. In general, the method comprises the step ofpositioning a preformed frusto-conical blank 5d of foamed plastic sheetmaterial, which forms the outer peripheral wall portion 26 or 29' of thecompleted container, within a die cavity and then drawing a heated sheet52 of solid plastic into engagement with the blank so as to conform thesheet and blank to the configuration of the die cavity. In FIGURES 8- 12there is illustrated one method of forming the preformed blank of foamedplastic material and in FIG- URES l4l8 a preferred method of drawing theplastic sheet into a die cavity is shown. While this latter method isillustrated as being preferred, it will be understood that the containerdescribed above may be constructed by other methods.

Referring now more particularly to FIGURES 813, in constructing thepreformed frusto-conical blank 50 of foamed plastic material, it ispreferable to utilize foamed material in sheet form. The foamed plasticsheet material is first positioned into two superposed plies, asindicated at 54 and 55 in FIGURE 9. With the two plies in superposedposition, two pieces 58 and 69 in the form of a segment of a circularband are severed from the plies 54 and 56. One embodiment of a cuttingtool for severing the pieces 53 and 6t from the plies 54 and se isillustrated in FIGURES 8 and 9 and generally indicated at 62. Thecutting tool 62 includes a suitable frame 64, having a peripheralcutting blade 66 corresponding to the shape of the pieces 58 and 6textending downwardly therefrom. The two arcuate portions of the blade 66are provided with relatively sharp cutting edges as indicated at 68,while the two straight portions are provided with relatively blunt ordull cutting edges, as indicated at 79 and shown somewhat exaggerated inFIG- URE 9.

In addition, the cutting tool 62 may be provided with a plurality of pin72 arranged to cooperate with an apertured plate 73 to pierce the pieces58 and 6% during the peripheral severing operation so as to provide theopenings 22 previously described.

The provision of the relatively blunt or dull cutting edges 70 is ofsignificance in that it has been found that by providing such cuttingedges securement of the straight edges of pieces 53 and 60 is obtainedduring the movement of the cutting tool 62 into cutting engagement withthe plies 54 and 56 of the foamed sheet material against the plate 73.The relatively sharp cutting edges 68 along the arcuate portions of thecutting blade 66 sever these portions of the pieces 53 and 6%) from theplies with a scissors or shearing action by cooperation with the plate73 without any tendency for the edges of the pieces to adhere together.Thus, by severing the pieces from the plies, as indicated above, thestraight edges of the pieces are secured together as a result of thefusion occurring when the material is pinched between the blunt edges 70and the plate 73, so that the two pieces can then be opened to form thefrusto-conical blank 59, as indicated in FIGURE 10. In this regard itwill be noted that the fusion of the straight edges can occur withoutthe necessity of adding heat to the cutting edges 70 although under somecircumstances it may be preferable to heat the blunt cutting edge 70 toobtain a more secure bond or fusion between the adjacent edges of theplies. The blank 50 shown in FIGURE 11 is formed in the same manner asthe blank shown in FIGURE 10, except that rather than utilizing the pins68, the grooves 43 are embossed in the pieces 58' and 60 during thecutting action by suitable embossing elements (not shown) embodied inthe cutting tool 62, in lieu of the pins '72..

In one embodiment of the present invention not illustrated, the pinholes are formed simultaneously with the formation of the fused sideedges at one station by one tool and then the blank is severed from theplies at a second station by a second tool operable to cut by a shearingaction the arcuate edges of the blank.

It will be understood that the pin holes 22 may be formed in the sheetmaterial prior to the cutting action of the arcuate edges, as may theembossing of the grooves 43. Moreover, various designs, insignia,lettering and the like may be embossed in the sheet material prior to,during or after the cutting of the pieces. FIGURES 12 and 13 illustratetwo variations of a watfie type embossrnent which may be formed in thesheet material prior to the cutting of the pieces 58 and 60 therefrom.In FIGURE 12 the embossment is in a checkerboard formation wherein everyother square of the checkerboard is embossed in an opposite directionfrom the adjacent square, as indicated at 74 and 76. The embossment asshown in FIGURE 13 is in the form of a series of intertitting, dome-likeembossments of generally rounded triangular configuration, as indicatedat 78. It will be understood that sheet material embossed as indicatedin FIGURE 12 or 13 as well as other types of embossing designs may beutilized to form the plies from which the pieces 58 and 6d are cut toform the preformed frusto-conical blank Sll of foamed plastic material.

Rererring now more particularly to FIGURES 1418 there is shown therein amold, generally indicated at El which is constructed generally inaccordance with the construction of the mold disclosed in Caineapplication Serial No. 711,739, the disclosure of which is herebyincorporated by reference into this application. The mold 8t) includes adie cavity $2 which conforms in shape to the exterior shaee or" thecontainer ltl. Formed on the mold in surrounding relation to the upperopen end of the die cavity 32 is a ring 84 arranged to receive on itupper surface the sheet of plastic 52 which is to be drawn into the diecavity. Cooperating with the mold is a plunger assembly, generallyindicated at 86, which includes a centrally apertured disk-like member88 arranged to engage the upper surface of the plastic sheet when thelatter is in supporting relation to the ring 84 so as to maintain thesheet in pressure-tight engagement with the ring. The plunger assemblyalso includes a separately reciprocable plunger 9t) having a centralquenching air inlet passage 92 extending therethrough and a plurality ofbranch air inlet passages 93 extending radially therefrom adjacent theupper end portion of the plunger. Formed on the upper end of the plungeris an annular flange or shear plate 94 which is provided with aplurality of annularly spaced restricted air outlet passages 96. Thelower surface of the shear plate 94 is arranged to engage with a bluntcutting edge 98 formed in the mold in surrounding relation to theportion of the die cavity which forms the rim of the container. Asshown, the mold itself is provided with passages nae for communicating afluid under a negative pressure or vacuum to the portion of the diecavity adjacent the edge 9% and to the portion of the die cavitydefining the bot tom of the container to be formed.

As shown in FIGURE 14, the container of the present invention is made byfirst inserting the preformed blank 5a) of foamed plastic material intothe die cavity 82 of the mold St Next, the sheet of plastic material 52,heated as by direct passage from an extruder, is positioned above thering 8- 1 and the aperture disk member 88 of the plunger assembly isengaged on the upper surface of the sheet so as to provide an air-tightseal between the sheet material 52 and the ring 84, as shown in FIGURE15. Next, the plunger E is moved vertically relative to the mold so thatthe plunger enters into the die cavity 82 carrying with it the centralportion of the sheet held to the ring. Insofar as the precise action ofthe plunger on the sheet of plastic is concerned during its downwardmovement into the die cavity, reference can be had to the detaileddescription contained in the Caine application. Suffice it to say atthis time that the passages Mill in the mold are sealed ofi or otherwiseback-pressure controlled so that the air within the die cavity 32 willbe compressed during the movement of the plunger therein, thusmaintaining the sheet material out of contact with the blank 59 disposedwithin the die cavity adjacent the walls thereof.

When the plunger reaches approximately of an inch from the full extentof its movement within the die cavity, as shown in FIGURE 16, passagesltlll in the mold are communicated with a vacuum source, so as to drawthe sheet of plastic 52 moved into the die cavity by the plunger intocontact with walls of the die cavity to engage the pre-forrned blank 56disposed therein and conform the latter as well as the plastic sheetitself to the configuration of the die cavity, as shown in FIGURE 17.

The above operation is performed generally in accordance with thedisclosure of the previously mentioned Caine application. In the normaloperation of the structure of the Caine application, passage 92 isoperable to permit atmospheric air to enter the space defined betweenthe interior of the sheet conformed with the die cavity and the exteriorsurface of the plunger during the movements of the sheet into conformitywith the wall of the die cavity. For present purposes, it is necessaryto maintain the temperature of the blank 53 below a predeterminedtemperature within the time period during which expansion will occur.Consequently, in forming the container of the present invention, thereis provided an air quenching system which serves to maintain thetemperature of the blank within the tolerable limits during theformation of the container.

Insofar as the present operation is concerned it has been found thatthere is no necessity to permit the entrance of atmospheric air throughthe passage 92 during the vacuum drawing step since any air which istrapped between the sheet and the plunger will become heated and thusreadily expand during the drawing step. Immediately following the startof the vacuum drawing operation the plunger will descend to its fullyextended position, as shown in FIGURE 18, to first effect a seal betweenthe sheet 52 contacted by the shear plate 94 and then finally to effecta shearing against the shear ring $8. During this procedure air underpressure is delivered through the passage 92 and branch passages 94(from a suitable source not shown) at a pressure sufficient to cause theheated air between the sheet and the plunger to pass outwardly throughthe restricted outlet passages 96. The inlet pressure and the size ofthe orifices in the outlet passages are such that sufiicient evacuationor displacement of the heated air within the space between the sheet andthe plunger takes place that the eated air is replaced by the incomingcooler air under pressure thus effecting an immediate reduction orcontrol of the decrease in the temperature of the sheeet and blankconforming to the walls of the die cavity.

The method as described above is preferably carried out with the use ofpolystyrene, both as the sheet material 52 which is drawn into the diecavity, and as the foamed sheet material utilized to form the pre-formedfrusto-conical blank 5%. it is preferable to use the same material forboth sheets for the reason that an extremely intimate bond between thetwo materials is obtained in the process, and any rejects or imperfectcontainers which are formed during the operation could not beeconomically salvaged for reuse as basic plastic material orre-circulation to the extruder unless the same material is utilized bothas to the plain sheet material and the foamed sheet material. Stateddifferently, if the two sheet materials are of a different plastic, itwould be economically feasible to separate the two after imperfectformation, so as to reclaim separately the two plastics utilizedtherein.

The present invention is by no means limited to the use of polystyrene.For example, the following are illustrative examples, of various plasticmaterials which may be utilized, it being understood that while it ispreferable to utilize the same plastic material both for the solid sheetmaterial and the foamed sheet material, that different plastic materialsmay be utilized if desired.

Thus there also can be used as the plastic vinyl type plastics such aspoly alpha methyl styrene, polyvinyl toluene, polyvinyl chloride,polyethylene, vinylidene chloride polymer coated on polyethylene,polypropylene, irradiated polyethylene, eg. irradiated to an extent of 2to 25 megarep, polyurethanes, eg the reaction product of toluenediisocyanate and an ester such as trimethylol propane modifiedpolyethylene adipate having hydroXy end groups or the reaction productof toluene diisocyanate with polypropylene glycol molecular weight 2025,the reaction product of toluene diisocyanatc with tris poly- Cit 3propylene glycol 2025 phosphite, vinyl chloride vinyl acetate copolymer,polyesters such as polyethylene terephthalate, polyamides of the nylontype, e.g. polymeric hexamethylene adipamide, styrene-acrylonitrilecopolymer.

The foamed plastic sheet can be made by foaming any of the plastics setforth above or can be a different foamed material such as foamed naturalrubber, foamed synthetic rubber, e.g. foamed butadiene-styrenecopolymer.

The presently preferred foamed sheet materials are foamed polystyreneand foamed polyurethanes.

The plastic materials should be selected so that they will not melt orunduly soften at the temperature of hot water. Preferably the plasticchosen should not soften at 100 C.

It will be understood that a container made in accordance with themethod described above would have generar utility not only as drinkingglasses for liquids, both hot and cold, but as storage containers orpackaging containers for any liquid or semi-solid material. Thecontainer described above is particularly suited for use in hot drinkdispensing or vending machines. The requirements of a container whichwill successfully function in a vending machine are quite severe and anycontainer which will meet these requirements will perform quitesatisfactorily in other one shot uses, as, for example, in carryoutrestaurants and the like, or for home use. With respect to therequirements of a container for a hot drink vending machine it should benoted first that there is a limited space within the vending machine tostore a supply of containers. For this reason the containers must be ofthe nestable type. Moreover, the containers must be stacked in nestedrelation so that the lowermost container of the stack will be freelyremovable from the stack. That is, any tendency for the stackedcontainers to stick into nested relation would tend to cause the vendingmachine to malfunction and prevent the container dispensing mechanismfrom properly depositing a container into proper position to receive theliquid dispensed. The stacking means provided by the present inventionamply meets these requirements. First, it will be noted that the wallsections 32 providing the upper stacking surfaces of the container arespaced apart a distance less than the width of the wall section 4-0,which provides the downwardly facing stacking surfaces, an amountgreater than twice the wall thickness of the bottom. With theconfiguration illustrated, these stacking surfaces will be in alignmentin only two positions of relative rotation between any two containers.Of course, when the two surfaces are out of alignment there will be fulltransverse engagement of the surfaces positively preventing wedgedengagement of the two containers. Even when the containers are alignedas shown in FIGURE 3, the relative spacing of the surfaces is such thatthere is positive contact preventing the containers from becoming wedgedtogether. Moreover, it will be noted that the upwardly facing surfacestend to move together by virtue of the angular disposition of the wallsection 36 in response to increase in load on the surfaces. Thus, evenin a relatively high stack of containers there is positive preventioneven of the lowermost containers from becoming wedged together.

The provision of the stacking means in the bottom of the container isregarded to be advantageous from the point of view that it enables thecontainer to have a com.- pletely uniform peripheral wall 14. Theupwardly projecting wall sections 32, 34, 36 and 38 provide a falsebottom effect in the container. However, since the bottom is irregular acertain amount of turbulence is imparted to any liquids poured into thecontainer which aids in mixing the contents.

The particular stacking construction also has advantages when utilizedin the preferred method of construction. The inverted V-shaped wallsection, after formation, will yield inwardly so as to permit thecontainer to be easily removed from the die cavity. It will beunderstood that the portions of the die cavity which form the upwardlyand inwardly converging wall sections present some diihculty ofcontainer removal after formation, but with the above-mentioned actionthis removal is simplifled. Furthermore, with the peripheral rim sectionthere is provided adequate supporting surface for the container while atthe same time, the radial groove 28 prevents hot gases from beingtrapped by the annular surface which may have the effect of condensingvapor on the surface which supports the container when hot liquids areheld in the container. Thus, the radial groove 28 as well as theupwardly projecting wall sections afford adequate air circulation underthe bottom of the container when it is resting on a horizontal surface.

it will be understood that the vertical distance between the upwardlyfacing stacking surface of the wall sections 32 and the downwardlyfacing stacking surfaces of the wall section 40 is of a minimum distancesufficient to provide a minimum stand ofi distance between the innerwall portion 20 of the lowermost container of the stack and the outerwall portion of the container nested therein, preventing these wallportions from wedgingly engaging each other. The vertical distancebetween the upper and lower stacking surfaces provided by the containerdetermines the number of containers which can be stacked within a givenstorage space within the vending machine. As indicated above, this spaceis limited and it is highly desirable that a maximum number ofcontainers can be stored in this space. The minimum vertical dimensionbetween the upper and lower stacking surfaces or stacking heightprovided by the container is limited by two considerations: first, thewall thickness of the container; and second, the angle of taper of theperipheral wall. For practical purposes the angle of inclination of theperipheral wall must be greater than in order to permit nesting and lessthan 90 to enable the container to hold material. The intermediate angleutilized is dictated to a large extent by the general size andproportion of the container desired. For any given size of container,the angle of taper of the peripheral wall cannot be too great inrelation to the height of the container, or else the bottom surface willbe too small to stably support the container when filled with material.However, from the point of view of minimizing the stacking height, theangle of taper of the peripheral wall should be as great as possible. Ithas been found that an an le of taper on the order of between 410presents a practical range and, of course, the minimum stacking heightfor any given wall thickness within this range increases as the angle oftaper decreases. Conversely, for any given stacking height the maximumwall thickness which can be utilized increases as the angle of taper ofthe peripheral wall increases.

A preferred embodiment of a 6 ounce container constructed in accordancewith the principles of the present invention has an angle of taper of 7%a stacking height of A inch, and a peripheral wall thickness includingthe foam that varies from a minimum of .020 inch to a maximum of .028inch in accordance with the variations in wall thickness as disclosed inthe aforementioned Caine application.

= 'n the practical limits of a container which is satisfactorilyproportioned and sized for vending machine use, the wall thickness willhave a determining factor on the minimum stacking height that can beprovided. In some instances it is permissible to utilize a thin-walledcontainer, but where such containers must hold hot liquids, such ascoffee and the like, the thickness of the wall does not normally oifersut'ficient insulation to permit the user to hold the container with thehot liquid therein without some unpleasant sensation. It has beenproposed to modify the configuration of the wall without increasing thethickness thereof, so as to provide optimum heat transfercharacteristics to the wall. An example of a container constructcd withthis principle in view is shown in the abovementioned co-pending Caineapplication. While containers of this type have received someacceptance, they are still somewhat difiicult to handle with hot coffeeand other hot drinks. The mere provision of additional material in thewall does not provide an adequate solution because of the increasedcosts involved. Moreover, the amount of solid plastic necessary toprovide better insulating qualities would not only be prohibitive from acost standpoint, but would be of such extent that the stacking heightwould be increased substantially.

The present container achieves the necessary improved insulatingqualifications with the addition of a minimum amount of material addinga minimum thickness to the peripheral wall of the container so as toachieve the desired result without too much increased cost or increasedstacking height.

0f primary significance is the fact that the material is capable ofexpansion in response to exposure to temperatures of the typeencountered when the container is used for hot drinks such as coffee orthe like. Conversely, it would be undesirable if expansion occurred atambient temperatures or excessive temperatures which might beencountered in ambient conditions. The time of exposure to the excessivetemperature has a bearing on the expansion. Essentially the expansion iscaused by the material itself reaching a predetermined elevatedtemperature, the greater the temperature the greater the expansion.Thus, an instantaneous exposure to a highly elevated temperature wouldnot result in the material itself reaching such a temperature; whereascontinued exposure would result in the temperature of the materialreaching a point closely approximating that of the source.

From the above it can be seen that it is preferable that the materialhave a maximum expansion characteristic so long as there is notappreciable expansion under ambient conditions. A material which iscapable of expansion of approm'mately 200% at 212 F. and approximately20% at P. will achieve the desired result. A preferred material iscapable of expansion of approximately 350% at 212 F. and approximately40% at 170 F. The figures indicated above are those obtained bysubjecting the material by itself to an oven temperature for a period oftime (approximately four minutes) sufficient to raise the temperature ofthe material to that indicated. It has been found that the amount ofexpansion increases as the temperature is increased within the rangeindicated. It will be understood that the percentage of expansion in thefoam material when embodied in the container having a liquid at atemperature of 170 F. and 212 F. will be less, the above figures merelyrepresenting a maximum. The longer that the liquid is retained in thecontainer the more nearly the expansion will approach the maximumfigures indicated.

The characteristic of the foam material to expand in response toexposure to elevated temperatures to the ex tent indicated above can beachieved in several different ways. First, where the foamed material hasa closed cellular structure it is entirely possible that the gaseswithin the closed cells will expand when exposed to elevatedtemperatures, thus expanding the material. This characteristic may alsobe built into the product by stopping the foaming action during theformation of the material, so that there will be residual blowing agentremaining therein capable of being reactivated when the material isagain exposed to elevated temperatures. Another way of achieving thischaracteristic in the material is to mechanically compress the materialas by running the same through calendering rolls or the like. The exactmanner in which the characteristic is built into the material utilized,whether by one or more of the procedures indicated above or otherwise,is of no great importance so long as the material utilized has thecharacteristics indicated. With such characteristics it will be notedthat the wall thickness added by the provision of the foamed materialwill be at a minimum, thus maintaining a minimum stacking height withthe container.

When a hot liquid is poured into the container, as during the normal useof a hot drink Vending machine, the heat of the liquid will be conductedto the foamed materia1, causing the same to expand. This expansionincreases the insulating characteristics of the container and suchincrease in the insulating properties becomes greater as the need forsuch properties increases. That is, the hotter the liquid within thecontainer, the greater the expansion and hence the greater theinsulation provided. The extent of expansion is such that, once thecontainer has been exposed to temperature conditions at least of thetype encountered when the container is used with hot drinks, the wallthickness will have increased to a dimension greater than that providedby the stacking height of the container necessary to permit thecontainers to freely nest within one another. In other words, once thecontainers have been exposed to the elevated temperature such as ispresent when hot drinks are in the containers, the containers could notbe freely nested together to an extent such that they could be dependedupon to operate in a vending machine container dispensing mechanism. Inthis way a minimum amount of plastic material which will afford thegreatest possible insulating properties is utilized and the constructionis such that the wall thickness when the container is in stackedrelation where the insulating properties are not needed is less, thuspermitting a desired minimum stacking height and yet when the insulatingproperties are needed, they are available on demand to an extent greaterthan that afforded by the material in its initial thickness. Thisproperty of the present construction makes it possible to achieve adesired minimum stacking height while maintaining manufacturingtolerances in wall thickness which simply could not be utilized in theabsence of such expansion without an undesirable sacrifice in theinsulation properties of the containers.

From the above it follows that during the drawing of the heated plasticsheet 52 into the die cavity into contact with the frusto-conical foamedblank, provision must be made to maintain the temperature exposureconditions of the blank except on the solid plastic contacting surfacethereof below approximately 170 F. for the period of time within whichexpansion will take place. The air quenching system previously providedis normally capable of obtaining this end although it may be desirablein some instances to provide the mold with a cooling liquid adjacent thesurfaces which form the peripheral wall of the container.

It can be seen that the container of the present method cannot bepractically formed by first laminating the solid plastic with the foamedplastic and drawing the laminate into the die cavity, since the heatrequired in the drawing action would destroy the expansioncharacteristics. Even if the drawing operation could be done cold, therewould be considerable destruction of the cellular construction of thefoamed material in the drawing procedure. It would be possible toinitially form the unitary shell of the container and then tosubsequently apply a band of foamed material to the exterior peripheralwall of the shell. Such a method of forming the present container isdisclosed in the commonly assigned United States application Serial No.208,867 filed July 10, 1962 concurrently herewith in the name of WalterO. Weber.

It will also be understood that in conjunction with the expansion of thefoamed material for insulating purposes, the stiffness of the containeris also increased by the expansion. Another advantage of the presentconstruction is that the orientation of the foamed material is differentfrom the orientation of the solid plastic material. It is Well-knownthat a drawing operation has a tendency to orient the plastic so that itwill tend to fail by fracture longitudinally down the peripheral wall.The container made in accordance with the present method effects anexcellent bond between the solid plastic and the foamed i2 plastic but,of course, does not disturb the normal orientation of the foamedmaterial. In this way the foamed material would tend to resist anycracking in the direction of orientation of the solid material.

With respect to the bonding of the solid plastic material with thepre-formed frusto-conical foamed plastic blank, an excellent bond isachieved in the normal steps of the procedure. However, care must betaken to permit he surfaces of the two materials to intimately contacteach other and therefore, where the foamed material is of a closedcellular construction, it is possible to trap pockets of air between thetwo plastic materials unless provision is made to insure that such airis allowed to pass from between the two materials as they are movedtogether. it is for this reason that in the preferred container it), thepin holes 22 are formed in the blank. It will also be noted that wherelongitudinally extending embossed grooves 48 are formed in the blank, asshown in FIGURES 7, 8 and 11, these grooves will provide passages toallow any air between the two materials to escape. Likewise, theembossed foamed material as shown in FlGURES 12 and 13, would permit theair to pass from between the two materials.

The foamed material is easily embossed prior to formation resulting inan image formation in the solid plastic during formation so thatdesigns, letters and other indicia may be provided without the necessityof utilizing inks or other coloring. In addition, however, where thefoamed material is of a closed cellular construction, the exteriorsurface thereof will readily receive any type of printing.

it thus will be seen that the objects of this invention have been fullyand effectively accomplished. It will be realized, however, that theforegoing specific embodiment has been shown and described only for thepurpose of illustrating the principles of this invention and is subjectto extensive change without departure from such principles. Therefore,this invention includes all modifications encompassed within the spiritand scope of the following claims.

What is claimed is:

it. A thin Walled nestable container comprising a container bodyincluding a bottom and an upwardly and outwardly tapering peripheralwall extending upwardly therefrom so as to enable said container body tobe nested within a similar container with the peripheral wall of saidcontainer body inside the peripheral wall of the similar body, saidbottom having a pair of upwardly projecting portions spaced inwardlyfrom said peripheral wall and defined by a plurality of thin walledsections disposed in concavo-convex relation, the thin walled sectionsdefining each upwardly projecting portion including an upwardly andinwardly extending arcuate walled section, an upwardly and inwardlyextending straight walled section disposed between the ends of saidarcuate walled section, and an arcuately segmental walled sectionextending horizontally between the upper edges of said arcuate andstraight walled sections, said pair of upwardly projecting portionsproviding a pair of upwardly facing horizontally extending stackingsurfaces spaced horizontally apart, said bottom including a pair ofdownwardly facing horizontally extending stacking surfaces spacedhorizontally apart a distance which is greater than the distance betweensaid upwardly facing stacking surfaces an amount greater than twice thewall thickness of said bottom.

2. A container as defined in claim 1 wherein said bottom includes ashallow inverted V-shaped wall section extending between said straightwall sections.

3. A container as defined in claim 2 wherein said bottom includes arelatively narrow horizontal rim portion adjacent said peripheral wallhaving a radially extending groove formed therein.

4. A container as defined in claim 1 including a layer of foamed plasticmaterial adhered to the exterior surface of said peripheral wall anddisposed at least in the area thereof which would normally be gripped tohold the container body, said layer of foamed plastic material beingexpansible to increase the stiffness and insulating properties of saidperipheral wall in response to exposure to the temperature conditionsencountered when hot drinks are contained therein to an extent such thatsaid container body after expansion will not nest freely with a similarcontainer body.

References Cited by the Examiner UNITED STATES PATENTS 2,737,332 3/56Amberg 2291.5

Lattuca.

Politis 1819 Politis 1819 Witzke 229-1.5

Caine 229-1.5

Shappell 2291.5 Edwards.

Fibish 2291.5

Edwards 229-1.5 X

Schechter 2291.5

GEORGE O. RALSTON, Primary Examiner.

1. A THIN WALLED NESTABLE CONTAINER COMPRISING A CON TAINER BODYINCLUDING A BOTTOM AND AN UPWARDLY AND OUTWARDLY TAPERING PERIPHERALWALL EXTENDING UPWARDLY THEREFROM SO AS TO ENABLE SAID CONTAINER BODY TOBE NESTED WITHIN A SIMILAR CONTAINER WITH THE PERIPHERAL WALL OF SAIDCONTAINER BODY INSIDE THE PERIPHERAL WALL OF THE SIMILAR BODY, SAIDBOTTOM HAVING A PAIR OF UPWARDLY PROJECTING PORTIONS SPACED INWARDLYFROM SAID PERIPHERAL WALL AND DEFINED BY A PLURALITY OF THIN WALLEDSECTIONS DISPOSED IN CONCAVO-CONVEX RELATION, THE THIN WALLED SECTIONSDEFINING EACH UPWARDLY PROJECTING PORTION INCLUDING AN UPWARDLY ANDINWARDLY EXTENDING ARCUATE WALLED SECTION, AN UPWARDLY AND INWARDLYEXTENDING STRAIGHT WALLED SECTION DISPOSED BETWEEN THE ENDS OF SAIDARCUATE WALLED SECTION, AND AN ARCUATELY SEGMENTAL WALLED SECTIONEXTEINDING HORIZONTALLY BETWEEN THE UPPER EDGES OF SAID ARCUATE ANDSTRAIGHT WALLED SECTION, SAID PAIR OF UPWARDLY PROJECTING PORTIONSPROVIDING A PAIR OF UPWARDLY FACING HORIZONTALLY EXTENDING STACKINGSURFACES SPACED HORIZONTALLY APART, SAID BOTTOM INCLUDING A PAIR OFDOWNWARDLY FACING HORIZONTALLY EXTENDING STACKING SURFACES SPACEDHORIZONTALLY APART A DISTANCE WHICH IS GREATER THAN THE DISTANCE BETWEENSAID UPWARDLY FACING STACKING SURFACES AN AMOUNT GREATER THAN TWICE THEWALL THICKNESS OF SAID BOTTOM.